In the overview of DNA replication, which enzyme is primarily responsible for unwinding the DNA double helix at the replication fork?

• A. DNA helicase
• B. DNA polymerase III
• C. Primase
• D. DNA ligase

Answer: (A)

Verified step by step guidance

1. Understand the process of DNA replication, which involves unwinding the double helix, synthesizing new strands, and joining fragments.
2. Identify the role of each enzyme listed: DNA helicase, DNA polymerase III, primase, and DNA ligase.
3. Recall that DNA helicase is the enzyme that unwinds the DNA double helix by breaking hydrogen bonds between base pairs at the replication fork.
4. Recognize that DNA polymerase III synthesizes the new DNA strand by adding nucleotides complementary to the template strand.
5. Note that primase synthesizes RNA primers to initiate DNA synthesis, and DNA ligase joins Okazaki fragments on the lagging strand.